Steady state and picosecond time-resolved photophysics of a benzimidazolocarbocyanine dye

We report the steady-state and the excited state properties of 1, 3, 10, 30-tetraethyl-5, 6, 50, 60-tetrachlorobenzimidazolocarbocyanine iodide (TTBC) in various solvents. The magnitude of the Stokes shift and the average transition energy proves that the structure of the fluorescent state should be very similar to that of the ground-state structure. The fluorescence lifetimes and quantum yields indicate that non-radiative processes are collectively much more effective than the radiative processes. It is therefore suggested that the non-radiative processes, which are driven by the medium around the TTBC molecule control the excited state dynamics. r 2002 Elsevier Science B.V. All rights reserved.